1. Field of the Invention
The present invention generally relates to a clutch disk for clutch disk assembly. More specifically, the present invention relates to a clutch disk assembly with a clutch disk, which together form a part of clutch device.
2. Background Information
A clutch disk assembly is a device for transmitting a torque between a first rotary member on an input side and a second rotary member on an output side. A clutch disk assembly generally includes a clutch disk having a pair of friction facings, an input plate to which a clutch disk is fixedly coupled on the outer circumference, an output hub, and a dampening part to connect the input plate and the output hub in a circular direction. In the clutch disk assembly, when one of the friction facings is pressed against a flywheel on an engine side by a pressure plate of a clutch cover assembly, the clutch disk is held between the flywheel and the pressure plate, and a torque of the flywheel on the engine side is input to the input plate via the clutch disk. The torque is then transmitted to the output hub via the dampening part, and is output to a shaft on an output side.
Thus, a torque is transmitted when the clutch is connected by pressing the clutch disk against the flywheel. In order to ease a shock in connecting the clutch, a cushioning plate is used for some clutch disks. Generally, six to nine pieces of cushioning plates are used in a circular direction. Since each cushioning plate has a wavy shape in a circular direction, the cushioning plate deforms elastically when the clutch disk is pressed against the flywheel. The elastic deformation works as a cushion, leading to easing a shock in connecting the clutch. The friction facings are annular members, which are typically installed in opposite side surfaces of a cushioning plate by rivets.
However, when rivets are used as described above, the thickness or length of the size of the clutch disk in an axial direction has some limitations. Therefore, it is thought that instead of using rivets, the friction facings can be installed by simultaneous moldings. However, when friction facings are installed by molding, the function of the clutch disk (referred to as a cushioning function hereafter) acting to absorb shock is lost.
One method, which has been developed to attempt to overcome such problems, is described in Japanese Laid-Open Patent Publication No. 59-50229. This publication discloses a method to install a friction facing in a fan-like configuration on the outer circumference of the disk plate which has an evenness divided in a circular direction by a radial cutout. In the method disclosed in Japanese Laid-Open Patent Publication No. 59-50229, a step-like part having a cushioning function is located in the inner circumferential side of the lining part (a part in which a facing is installed). Consequently, there is a difference between elasticity of the outer circumference of the lining part in an axial direction and elasticity of the inner circumference of the lining in an axial direction. Therefore, when a clutch disk is pressed against a flywheel by a pressure plate, an uneven load is applied to a friction facing because elastic reaction forces between the inner and outer circumferences of the lining parts are different. As the result, the friction facings are abraded eccentrically by repeating the clutch operation.
In view of the above, there exists a need for a clutch disk and clutch disk assembly which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.